History of the G-56 Controversy?

[Buffalo]

Today, I received a call from a Duramax friend of mine, who monitors this site, asking me what the story was behind all the controversy regarding the G-56. I, honestly, don't know the whole story. Could someone please tell us why this is such a hot topic.



What I do know is that it has a DMF, alum. case, different shift pattern for reverse, supposed to not support quite as much torque as the NV5600.

The rumor I heard was that the original trannies had the gear oil fill hole placed too low, therefore, not providing enough gear lube in the trans. I, also, heard that they started using another plug that was higher on the trans. case, therefore, raising the fluid level.



Another rumor was that DC stopped selling G-56 equipped trucks, at least, for awhile. My friend suggests that they stopped building the G-56's. I'm not sure about this, because, I had the opportunity to drive one a couple of weeks ago. My friend, also, said that He thought you couldn't order a new Dodge/Cummins with a G-56 until the '06's come out. Any truth to this? Is DC building new trans. cases with the fill hole placed correctly?



Anyone know of other uses for this trans. & how long it has been around? Basically, it's history?



I know this a very HOT topic on other threads. In no way do I want to throw Diesel Fuel on the fire. My friend and I would, sincerely, like to know what the history & story behind this transmission is, so that we may better understand why there are such heated discussions on this subject.



Thanks for your help.



Joe F. (Buffalo)

 

[dhill]

Controversy? What controversy? Just a bunch of good óle boys sitting around the camp fire passing the time of day.



Dave

 

[Gary - K7GLD]

Controversy? What controversy? Just a bunch of good óle boys sitting around the camp fire passing the time of day.



Dave

YUP, exactly!



We get tired of needling the Ford and GM crowd (WAY to easy to befuddle THEM!), and keep in practice by needling each other - better bunch anyway!

 

[AlexWV]

removed masked profanity

Here is the history. First there was a Getrag and it was . THen there was an NV4500 and it was good. Then there was a NV5600 and it was better. Then there was a G56 and it was. I think that about covers it.

 

[67guzzler]

Here is the history. First there was a Getrag and it was . THen there was an NV4500 and it was good. Then there was a NV5600 and it was better. Then there was a G56 and it was . I think that about covers it.

Alex -- I thought you liked yours...

 

[AlexWV]

I do like it. No worries. Just giving a brief version of the gospel as handed down by the TDR boards.

 

[67guzzler]

Gotcha! :-laf The jury is still out on the G-56 though. I'm trying to be open-minded



Speaking of which -- I just googled for dual mass flywheel and read a bunch of stuff. I saw this post in response to someone complaining about clunks on their 2005 STS on a Cadillac Board of all places:



"The clunk is the dual mass flywheel. I replaced mine with a lightweight unit, and no clunk under any conditions whatsoever. The flexible coupling in the 2 piece driveshaft is also a contributing factor. When the trans is disengaged by pushing in the clutch, part of the dual mass flywheel continues to spin. When the clutch is released, part of the flywheel spins and part of it [that is controlled by springs inside the flywheel] continues to turn. When this part "bottoms out" [turns as far as the springs allow it], it clunks. "



Similar to explanations I've seen here on this forum... . May just be endemic of the G-56 w/the dual mass flywheel... .

 

[Buffalo]

Six replies, so far, and still no answers!

Does anyone know the history of this trans?

Is the G-56 still being manufactured or is it on hold? I know there are some available on the lots. Are they just the leftovers?

Can You order one?

If they fixed the alledged problems, what did they do to correct the issues this trans was supposed to have?

I'm, in no way, trying to start another trans war. That's why I started a new thread. I'd just like to know what is it about the G-56 that caused it to be so controversial? I drove one & didn't notice anything odd about the way it worked.



Thanks.



Joe F. (Buffalo)

 

[gonzo2]

The G-56 is still being manufactured and recent deliveries seem to be working out. The hold was for a short time as there was a problem that seems to have been traced to initial lubrication quantities. Once that was figured out I have not heard of delays.



The controversy seems to be based on two main points.



The 5600 was excellent so why change.



The new dual mass flywheel.



If I ordered a new truck today (I'm not because I'm satisfied with my '03) I'd order the G-56, and compensate for the gearing with big honkin' tires.

 

[Gary - K7GLD]

As some have accurately pointed out, and to de-fuse any claims by the competing Ford and GM folks, the vast majority of G56 operating discussion relates to vague new noises - thumps, etc. , that apparently directly relate to the new dual mass flywheel in it's normal operation.



And even that apeears to be minimized as new owners become accustomed to the issue and adjust driving/shifting habits to comphensate - it's simply a new characterstic owners of the older transmission/flywheel need to get used to.



As to a precise "history" of the G56, I'm not sure any totally accurate info has yet been provided - as I understand it, the G56 WAS developed to replace the previous NV-5600, and a new plant (in Brazil?) built and staffed to manufacture the G56, primarily for use in the Dodge as I understand it - but I may be wrong on some of this, and really don't want to add more poor info on top of that you may already have been exposed to by friends...

 

[67guzzler]

Maybe this will be helpful?



http://www.benzworld.org/news/news. asp?id=106

 

[betterthanstock]

Maybe this will be helpful?



http://www.benzworld.org/news/news. asp?id=106

quote from above:

Transmissions G56, G60 and G85 have the respective torque of 580 (428 ft-lb), 600 (443 ft-lb) and 850 Nm(627ft-lb). Model G56 is applied to light vehicles, from 7 to 10 tons, and medium ones from 11 to 12 tons; model G60 may equip medium vehicles from 12 to 14 tons, and semi-heavy ones from 14 to 17 tons; and model G85 is destined to heavy vehicles.



I added ft-lb in parantheses.

Looks like getting rid of the dual mass f/w (like i've seen some posts) will shear the gears in short order. The dual mass smooths over the power pulses.

 

[CJ8Rockcrawler]

The other thing to keep in mind is even if it is designed for *only* 428 ft-lbs of torque in a 7-10 ton vehicle, there is probably a fair amount of safety/strength margin in our 3. 5 ton vehicles.

 

[RustyJC]

The other thing to keep in mind is even if it is designed for *only* 428 ft-lbs of torque in a 7-10 ton vehicle, there is probably a fair amount of safety/strength margin in our 3. 5 ton vehicles.

How many tons is your transmission having to move if you're pulling a 5th wheel that puts you at your rated GCWR? About 11. 5 tons (assuming 23,000 lbs GCWR)?



Rusty

 

[BHolm]

I don't think anyone can correctly predict how the G56 will fare in the real world. I am waiting and watching. The ratings do not inspire much confidence. We are right at the limits and actually above the torque rating with stock trucks, nevermind the proclivity to bomb these trucks. In my opinion the dual mass flywheel has never worked very well in any application I have read about. The STS story is more fuel for that fire IMO. The incorrect lube level and filling through the shifter is a worrysome fix.



The proof in the pudding will be as time passes, trucks get bombed, and faithful TDR members push the limits for science :-laf In a year or two I might be a G56 customer, IF it lives. For now, for me, I would buy a used truck with a NV5600 before I would offer to product test for DC. I say that because I was burned on the old Getrag they put in my '92. I had to have that one rebuilt 6 times in 200k miles, hated it.



I wouldn't worry about the d-max guys either. They have a pretty good set of issues on their 6 speed. they can't get the full power engine in front of it. I am pretty sure they have the same DMF issues and they are very hard to find.

 

[FATCAT]

I guess the history of the G56 comes down to the DC boardroom.



Who do you think made the decision to drop the NV5600 and go with the inhouse G56:



1. the DC engineers with the evidence that the G56 manual was a superior transmission in every respect and would be better for the consumer.

2. the CFO (Accounting) with a report on the per-unit-cost of going inhouse plus, the ability to give business to one of the Damiler units (to help their profit margins), built outside the US in that workers paridise of Brazil.



You make the call.

 

[67guzzler]

I guess the history of the G56 comes down to the DC boardroom.



Who do you think made the decision to drop the NV5600 and go with the inhouse G56:



1. the DC engineers with the evidence that the G56 manual was a superior transmission in every respect and would be better for the consumer.

2. the CFO (Accounting) with a report on the per-unit-cost of going inhouse plus, the ability to give business to one of the Damiler units (to help their profit margins), built outside the US in that workers paridise of Brazil.



You make the call.

FATCAT -- I think you've hit the nail on the head. I think it's #2. If I were DC, I'd do the same thing. Why give competition business when you manufacture truck transmissions yourself?

 

[RustyJC]

Why give competition business when you manufacture truck transmissions yourself?

Ummm... Daimler (Mercedes) and Detroit Diesel (a subsidiary) build truck diesels, you know...



Rusty

 

[67guzzler]

True... . But there is so much brand recognition with the Cummins / Dodge combo that I don't think dropping the CTD is going to happen soon. With the NV5600 there isn't such a relationship.

 

[Tim]

There is a contractural relationship at this time that prevents that. I have no doubt that once it ends, we'll have some sort of "other" Diesel involved.